Grappling with the generalizability crisis in addiction treatment research

Buprenorphine Naloxone and Extended Release Injectable Naltrexone for the Treatment of Opioid Use Disorder Among a Veteran Patient Sample: A Retrospective Chart Review

Previous research has demonstrated the effectiveness of both extended-release injectable naltrexone (XR-NTX) and buprenorphine/naloxone (BUP-NX) in the treatment of opioid use disorder (OUD). However, studies using real-world samples with multiple medical and psychiatric comorbidities are lacking. The study's primary aims were to: (1) compare clinical presentations in an inclusive sample of OUD-diagnosed US military veterans receiving XR-NTX and BUP-NX, and (2) investigate differences in 90-day treatment outcomes between these two groups. Methods: The medical records of 79 patients receiving medications to treat OUD in a VA hospital's addiction outpatient treatment program were reviewed retrospectively. The analysis included all veterans who initiated medication treatment during the study period. Differences between medication groups on co-occurring diagnoses, treatment retention, and related outcomes were examined. Results: The two groups were similar in medical and psychiatric comorbidity, although the BUP-NX group were more likely to have a pain diagnosis. No statistically significant differences in retention or toxicology results were found between the two groups over the 90-day study period. The rate of positive urine screens for the BUP-NX group was 19.2% for opiates and 13.5% for other illicit substances, and 3.7% and 11.1% respectively for the XR- NTX group. Conclusion: There was no evidence that 90-days outcomes differed for veterans based on medication received, and there were more similarities than differences in clinical characteristics. Additional research is needed, including larger sample size and prospective randomized control trial to evaluate VA patients' treatment outcomes receiving BUP-NX or XR-NTX for OUD.

Comparing adult cannabis treatment-seekers enrolled in a clinical trial with national samples of cannabis users in the United States

BACKGROUND

Cannabis use rates are increasing among adults in the United States (US) while the perception of harm is declining. This may result in an increased prevalence of cannabis use disorder and the need for more clinical trials to evaluate efficacious treatment strategies. Clinical trials are the gold standard for evaluating treatment, yet study samples are rarely representative of the target population. This finding has not yet been established for cannabis treatment trials. This study compared demographic and cannabis use characteristics of a cannabis cessation clinical trial sample (run through National Drug Abuse Treatment Clinical Trials Network) with three nationally representative datasets from the US; 1) National Survey on Drug Use and Health, 2) National Epidemiologic Survey on Alcohol and Related Conditions-III, and 3) Treatment: Episodes Data Set - Admissions.

METHODS

Comparisons were made between the clinical trial sample and appropriate cannabis using sub-samples from the national datasets, and propensity scores were calculated to determine the degree of similarity between samples.

RESULTS

showed that the clinical trial sample was significantly different from all three national datasets, with the clinical trial sample having greater representation among older adults, African Americans, Hispanic/Latinos, adults with more education, non-tobacco users, and daily and almost daily cannabis users.

CONCLUSIONS

These results are consistent with previous studies of other substance use disorder populations and extend sample representation issues to a cannabis use disorder population. This illustrates the need to ensure representative samples within cannabis treatment clinical trials to improve the generalizability of promising findings.

Exclusion criteria in treatment research on alcohol, tobacco and illicit drug use disorders: A review and critical analysis

ISSUES

High rates of exclusion in substance use disorder treatment studies reduce the external validity and clinical utility of research findings to an unknown extent. Accordingly, the current review examined commonly used exclusion criteria and their effect on study samples and outcomes.

APPROACH

English-language literature was identified by PubMed searches and review of identified articles' reference lists. Studies were included if they analysed data on: (i) the prevalence and nature of exclusion criteria in the substance use disorder treatment field; and/or (ii) the impact of exclusion criteria on sample representativeness or study results.

KEY FINDINGS

The search yielded 22 studies examining different aspects of exclusion criteria, including 15 empirical examinations of the impact of study exclusion criteria across different substance use disorder treatments on enrolment and outcome results. Aggregating across these 15 studies, we estimated that between 64 and 96% of potential study participants are excluded from substance use disorder treatment studies.

IMPLICATIONS

The widespread exclusion of large proportions of people with substance use disorders limits the external validity of the substance use disorder treatment research literature.

CONCLUSION

Although some eligibility criteria are necessary to protect participant safety and ensure internal validity, researchers conducting studies on substance use disorder treatments should thoughtfully consider the justification for and specific operationalisation of the extensive exclusion criteria they often utilise. [Moberg C, Humphreys K. Exclusion criteria in treatment research on alcohol, tobacco and illicit drug use disorders: A review and critical analysis. Drug Alcohol Rev 2017;36:378-388].